Resources

The
Columbia Basin Research preseason spring Chinook salmon run peak prediction
includes mean run timing as well as run size (www.cbr.washington.edu/inseason/adult
). Table 1 shows these results and other related
preseason predictions. Figure 1 shows the 2011 predicted size and timing
plotted with historical size/timing information using two methods: (A) defining
the run as between March 15 and June 15 the predicted run size is 209,000
spring Chinook, (B) defining the run size with a Gaussian arrival
distribution and no cutoff dates the predicted run size is 143,600 spring
Chinook. Brief details of the preseason predictions are below.

Table
1 Preseason Adult Spring Chinook Run Size Forecasts

Preseason Run Size Forecast

Data

Run Dates

Years

Method

Source

URL

198,400

Upriver
Spring Chinook, includes Snake
River summer Chinook and is sum of Bonneville Dam counts plus the
number of fish of upriver origin landed in lower river fisheries (kept catch
plus release mortalities). Forecast for 4 and 5-year olds.

Figure 1. (A) Historic median arrival day and cumulative counts during
counting period Mar 15 and June 15. (B) Peak Arrival Day and estimated spring
run as determined by fitting the spring run to a Gaussian distribution.
Points are in center of text. Blue-circled 2011 represents the estimated peak
timing and total run size based on the two runs size definitions as of March 23,
2011. Details of estimates are given below.

Preseason
Run Size Prediction

The
preseason adult run size used to be estimated using a linear regression of the
previous year's jack run size against adult run size using results since 1982
(1981 for Jacks). However, the relationship has been failing in recent years.
Beginning in 2010, an environmental variable is used along with historical
count data. Upwelling at 42 degrees North is highly
correlated with upwelling across the Northeastern Pacific, and is believed to
be an important harbinger of conditions because it is the approximate location
of the eastern end of the Sub-Arctic Current that divides to become the California Current and the Alaskan Current. Several other
measures of upwelling in various locations and times gave very similar results
(not shown). Figure 2 illustrates the regression obtained with run size
determined by cutoff dates (Method A):

Figure 2. Relationship of adult counts to previous
year's jack counts (spring run only). The 2011 preseason run size
prediction based on 2010 data for Method A or Method B (prediction highlighted
in blue).

Arrival
Distribution and Run
Peak

The
duration of the spring Chinook run is defined by two methods. Method A, which
is used for management of in-river harvest defines a
run as the total number of adult spring Chinook salmon passing Bonneville Dam
between March 15 and June 15 (date extended to include Snake
River destined summer Chinook). Method B, which is a better
ecological characterization of the spring run, simultaneously describes the
distributions of the spring, summer and fall runs by fitting three superimposed
normal distributions to the combined run (Figure 3). The mean arrival date of
each normal distribution characterizes the arrival peak independent of the
method used to determine run size. Details are available at, "Run timing
of adult Chinook salmon passing Bonneville dam on the Columbia River".

Preseason
Run Timing Prediction

The
spring Chinook peak run timing prediction (Anderson
and Beer. 2009. Oceanic, riverine, and genetic influences on
spring Chinook salmon migration timing. Ecological
Applications. 19(8):1989-2003.) is based on indices
of the run's genetically based run timing plus indices of the ocean and river
currents fish encounter on their homeward migration. The genetic run timing
basis is inferred from the timing of the previous year's jack run. The
effects of ocean currents encountered by both jacks and adults approaching the Columbia River are inferred from the January coastal
downwelling indices in the years of their respective returns. The river
velocities jack and adults encounter are inferred from river flows in the month
prior to their arrivals at Bonneville Dam. The model, calibrated with data
between 1978 and 2007, has an r2 = 0.78 (Figure 4).